The ability to remove the core of core locks is desirable in that it allows a lock to be changed by merely removing the lock's core and replacing it with another core operable by another key. U.S. Pat. No. 4,866,964 to Hall which issued Sep. 19, 1989 discloses a removable core cylinder lock which is normally operated by an operation key but is also capable of having its core removed by a second control key. The lock has a spring clip carried by its shell which cooperates with a groove in the core for normally retaining the core within the shell. The spring clip can be moved, however, to enable core removal by a control key. The control key has the same bitting as the general operation key. However, it is slightly longer so that it raises the spring clip out of the groove to allow the core to be removed from the shell as the core is rotated by turning the control key.
While the core lock assembly disclosed in U.S. Pat. No. 4,866,964 enables the core to be removed from the shell, the control key has the same bitting as the normal operation key. Accordingly, each lock has a control key as well as a normal operation key. This creates a situation which is clearly undesirable for owners of large numbers of such core locks since it forces the owners to not only keep an inventory of operation keys, but also an inventory of control keys.
Accordingly, an object of the present invention is to provide a core lock system, the locks of which can have their cores removed with a single control key.
Another object of the present invention is to provide a core lock assembly which is capable of being operated by at least two differently bitted keys to perform at least two different functions.